Perhaps you should try some spelling variations:
nam trung » nam trong, tai trung, ba trung
hieu van » hieu va, thien van, lieu va
nam truc » nam truoc, nam thuc, nam thuoc
hanh dai » hanh tai, hanh dao, vanh dai
tu sach » thu sach, su sach, te sach
ly nang » ky nang, ly hang, ly vang
xa hanh » xa thanh, xa khanh, va hanh
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, v nang, may nang

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ((y nang) OR (ly nang)) xa hoi. hieu van ((nam truc) or (nam trung)) xa hanh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((y nang) OR (ly nang)) xa hoi. hieu van ((nam truc) OR (nam trung)) xa hanh dai cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((y nang) OR (ly nang)) xa hoi. hieu van ((nam truc) or (nam trung)) xa hanh dai cua tre*".